contains all the sketches in this article. Also
included in the archive is a more robust
demonstrator of the Say It Module. This
demonstrator allows you to experiment with all
four command sets. It also provides more
verbose messages sent from the recognizer
module.

The Say It Module uses an on-board
microphone which is not ideal for robot control
(the EasyVR comes with a microphone on the
end of a short detachable cable). For best
reliability, you should speak no further than 2-3
inches from the microphone, and the mic should
be away from other sound sources. This pretty
much precludes putting the module and
microphone on the robot itself. Alternatives:
• Attach the microphone to a longer cable and
hold the mic in your hands. The cable should
be shielded and high quality, and not longer
than about five feet. Even then, this approach
may introduce too much noise in the
microphone signal.

are used to turn the servos on and off, respectively.

Important! The sketch in Listing 5 requires a separate
constants file, protocol.h. The file is too lengthy to present
here, but is included in the zip archive download that

62 SERVO 02.2012

Word to the wise: Be sure to turn off the TV, radio,
iPod, or any other sound-making source before
experimenting with voice recognition. The system works
best in a quiet room.